In last month’s issue we discussed how much water a substrate can hold and how much to replenish at various depletion levels, but not how quickly plants use water. A better understanding of plant water use will allow irrigation scheduling based on the plants rather than a set volume of water. There are several methods to determine how much water a plant uses in a day or a certain time period. Methods include determining leaching fraction (LF), using substrate moisture sensors, or by weight. Scheduling irrigation based on LF has been around for a long time. LF is the amount of water used over a certain period plus enough to cause a desired amount of leaching. To determine LF:

1. a. Overhead Irrigation: before a normally scheduled irrigation event place 5 to 10 potted plants of the same species individually into larger containers, such as a bucket, that fits tightly around the pot so that water entering the bucket has to go through the substrate.

   b. Micro-irrigation (individual plant): before a normally scheduled irrigation, place 5 to 10 potted plants individually into drip pans.

2. Make sure there is a large enough gap between the bottom of the bucket or drip pan and the pot so that water is not reabsorbed by the substrate, a 1 inch tall ring of PVC pipe or a block of non-absorbent material can be used to provide the gap, or with some buckets the pot may rest on the rim of the bucket so that there is a gap underneath.
3. a. Overhead: Do the same as 1a except with 5 to 10 of the same size but empty pots, no plant and no substrate.

   b. Micro-irrigation: place 5-10 emitters individually into a container that will collect the expected volume of water for the run time.

4. Run your irrigation system for the normal period, record the time.
5. Measure the volume of water collected in each bucket/container.
6. Average the volume collected from buckets with plants and average that collected from buckets without plants (or emitter containers), divide the average with plants by the average without plants, multiply by 100 to get LF (Table 1). See link 1 for an alternative method to determine LF.
7. You can measure distribution uniformity at the same time if you increase the number of empty containers or emitter only measurements and disperse these throughout your irrigation zone. See links 2 and 3 for methods to determine distribution uniformity.

If the LF is different from your target you can calculate the correct run time for the desired from the information collected:

RunTimeDesired = RunTimeMeasured x (100 – LFMeasured) / (100 – LFDesired)

Using the LF data in Table 1, where a low LF was used, suppose the soluble salts have risen above recommended levels and you want to provide a 25% LF irrigation. Also suppose the run time was 45 minutes. The run time needed for a 25% LF is:

RunTimeDesired = 45 x (100 – 10) / (100 – 25) = 54 minutes

After the 54-minute leaching irrigation you can go back to the 45-minute irrigation to conserve water. Just remember, as discussed in the previous article, when you go to low LF or other water conserving irrigation it is important to regularly monitor leachate pH and EC (link 4).

Many older recommendations target a LF of 10-20 percent, however, this is based primarily on greenhouse production. For nursery production, at least in the eastern U.S., LF can be much lower because plants periodically receive rain that will leach out enough salts to keep EC at acceptable levels. Since part of a leaner irrigation program includes monitoring EC at least monthly, LF can be increased periodically if EC begins to rise too high and then returned to the lower level as in the example above. Continuously leaching salts (fertilizers) from nursery crops is unnecessary unless there is a problem with high salts in the irrigation water. Consistently high EC with soluble salts in the irrigation water indicates the fertilizer rate may be too high resulting leaching out fertilizer you paid for. We have been irrigating woody plants at zero LF for over 10 years and have not had problems with high soluble salts even during a very dry growing season in Michigan with only 11 inches of rain. Nurseries in more arid regions and those with high soluble salts in their irrigation water that are considering irrigating at low leaching fractions must monitor leachate EC at least monthly to make sure salts are not building up.

We use sensors that measure substrate volumetric moisture content (SVMC- defined in last month’s article) to schedule irrigation. We have used both time domain reflectometry and capacitance sensors, currently we are using capacitance sensors. Handheld portable sensors or permanently placed sensors can be used and we have used both, currently we are using the latter. There are several brands and types of sensors available but make sure you get one appropriate for the expected use. Handheld sensors are rugged enough to be repeatedly inserted into substrates but not most permanent sensors. To determine plant water use with moisture sensors:

1. Irrigate to cause leaching out of the drain holes.
2. Wait 30 minutes to 1 hour to allow large pores to drain then measure SVMC with the sensor- this will give you container capacity (SVMCCC).
3. Wait 24 hours (or some other desired time interval) and measure SVMC again (SVMC24)
4. The difference between the measurements is how much water has been used by the plant and evaporated, or daily water use (DWU).
5. To determine how much water to apply to replace DWU: Gallons DWU = (SVMCCC - SVMC24) x container volume acre-inch to apply = gallons DWU x 231 / pr2 231 is the constant to convert gallons to cubic inches, pr2 is the area of the container top.

This calculation over-estimates to a minor extent since you don’t fill pots up to the very top with substrate. 

In steps 2 and 3, sample at least 10 pots for each species or similar water use group (Figure 1) and use the average in step 5. Step 2 should not be done every day, it defeats the purpose of improving irrigation practices to irrigate to drainage every day. Repeat step 2 monthly since CC often changes as plant roots fill pore spaces or substrates settle and shrink. Sampling with the handheld sensors (Figure 2) is very quick- just a few seconds each measurement- but still not something you want to do every day. Step 3 should be done each time you think the irrigation rate needs to be changed. When we used handheld sensors we would measure when there was a noticeable change in the weather (temperature, daylength, humidity, consistent periods of high winds) or approximately every 2 weeks (links 5,6,7). Our current permanently placed sensors provide continuous SVMC (link 7). Permanent sensors are usually part of an automated system that can be continuously monitored with computers (see links 8,9 for a description of these systems). Automated systems can be programed to replace daily irrigation or various other time intervals for more advanced irrigation management such as cyclic irrigation, set-point irrigation or other management needs. Replacing only DWU is basically the same as zero LF so monitor and manage EC as discussed for LF.

As an example of the above calculations, suppose your SVMCCC = 43% (step 2), your SVMC24 = 36% (step 3) and you are growing in true 3 gallon containers (not all 3 gallon containers have an actual volume of 3 gallons) with a top diameter of 11 inches or a radius of 5.5 inches. For individual container emitters we’ll use an application rate of 2 gallons per hour and for overhead irrigation a rate of ¾ acre-inch per hour.

Individual container emitters:

1. Gallons per plant DWU = (0.43 – 0.36) x 3 = 0.21 gallons
2. RunTimeDesired = gallons DWU / emitter application rate
3. RunTimeDesired = 0.21 / 2 = 0.105 hours = 6 minutes

Overhead irrigation

1. acre-inch to apply = (gallons DWU x 231) / pr2
2. acre-inch to apply = (0.21 x 231) / (3.14159 x 5.52) = 0.51
3. RunTimeDesired = acre-inch to apply / overhead application rate
4. RunTimeDesired = 0.51 / 0.75 = 0.68 hours = 41 minutes

Multiply acre-inch by 27,154 to determine the gallons per acre = 13,860

These calculations do not account for distribution uniformity. Divide runtime by distribution uniformity to correct.

Finally you can also determine DWU simply by measuring the weight of the containers at container capacity and 24 hours later. Divide the weight difference in pounds by 8.3 (water weighs 8.3 pounds per gallon). So if the difference in weight is 1.74 pounds, the DWU is 1.74 / 8.3 = 0.21 gallons. Use this DWU in the above calculations.

By knowing the DWU, we can start grouping plants with similar DWU into similar irrigation blocks. Measuring and replacing the exact DWU for each crop in is impractical but measuring a representative species for similar DWU groups will allow more efficient irrigation scheduling. A grouping based on DWU (averaged over the season) for plants grown at our research nursery is shown in Figure 1. Most plants had a DWU less than 5% SVMC (see last month’s article). Since local and daily climatic conditions will affect DWU, the amount of irrigation to apply will vary depending on time of year and geographic location but relative water use (high, medium, low) should be similar.

Most plants are tougher than we give them credit. Even if we don’t completely replace plant DWU, many plants grow well and sometimes better when irrigated slightly on the dry side. For 7 years our irrigation experiments with 3-gallon shrubs used ¾ acre-inch daily irrigation as control with treatments to apply 100 percent DWU, alternating 100 percent DWU with 1 or 2 days of 75 percent DWU (100-75 percent DWU, 100-75-75 percent DWU). For 30 out of the 37 species we’ve studied, we found the same or better growth for these treatments as for the control (Figure 3), we found lower growth with the control for four species (Figure 4) and lower growth for 100-75-75 percent DWU for three species compared to the control (links 5,6,7). We also found reduced foliar nutrient levels for several plants irrigated with the ¾ acre-inch rate compared to the other treatments (notice control plant chlorosis in Figure 4), indicating that we were leaching fertilizers out of the containers.

Irrigating with low to zero leaching not only reduces the amount of water used for irrigation but reduces the amount of runoff. Depending on species we have been able to reduce the amount of irrigation by 30-70 percent, the amount of runoff water by 30-85 percent and the amount of nitrate and phosphate in runoff by 30-50 percent. To attain results this high might be difficult for a commercial nursery with a much more diverse product mix but substantial reductions in water use, runoff and nutrient loss could certainly be attained.

When scheduling is done properly, it can result in more efficient water use, nutrients retained where they are available for plant uptake, reduced problems with alkaline water, reduced plant losses, improved plant growth and quality, shortened production cycle, less runoff and less off-site movement of water and nutrients.

R. Thomas Fernandez is a professor in the Department of Horticulture at Michigan State University; fernan15@msu.edu. The author wishes to acknowledge the many years of support from Spring Meadow Nursery, Inc., Renewed Earth LLC, Harrell’s Fertilizer, USDA NIFA Hatch Project MICL 02473, USDA SCRI Clean WateR3 – Reduce, Remediate, Recycle Grant Number 2014-51181-22372, MSU Project GREEEN, Michigan Department of Agriculture and Rural Development. I would also like to thank my former graduate students Aaron Warsaw and Nicholas Pershey, much of whose research contributed to this article.

Bailey Nurseries, a fifth-generation company, will launch a new corporate brand identity this summer.

“It’s more than a new logo. It’s a reflection of a new direction,” says Alec Charais, marketing and communications manager at Bailey. “When we took a look inward, we knew it was a good opportunity to move the brand forward and clarify our position that we’re focused on and committed to innovation.”

That new direction started some three years ago when Bailey Nurseries acquired Plant Introductions Inc. (PII), the breeding company founded by Michael Dirr, Mark Griffith and Jeff Beasley. Some of Bailey’s top sellers came from PII genetics.

“We are so fortunate to have had Mike [Dirr], Mark and Jeff and what they built. You can’t put into words what the three of them did as a team. They really created something special,” Charais says.

With the push toward more cohesive breeding activities, Bailey grabbed the opportunity to create a fresh, modern approach to its brand, Charais says.

“We feel extremely fortunate to have the equity of our brand to make a move like this. Whether it’s liners for growers or finished product for retailers, that part of our business is as robust as ever. We couldn’t make these changes without the strong customer support that we receive, which is what has built our brand over the long term,” he adds.

The new look comes with a renewed focus on breeding, now that Bailey’s Winterville, Ga., site is up and running. It’s home to Bailey Innovations, the nursery’s product development division.

And a new team is in place at the Georgia location. David Roberts is the general manager and lead breeder at Bailey Innovations and is joined by breeders Oren McBee and Justin Schulze.

“Those three are really focused on continuing the breeding matrix of specific types of genetics Bailey has identified as vital to its brand,” says Terri McEnaney, president of Bailey Nurseries. “They’ll continue to grow that pool of genetics and continue to get the product introduced successfully, not just in the U.S., but internationally, as well.”

The Georgia facility, Bailey’s southernmost location, will be built in phases.

“With this new location, our existing sites and our network of growers, we’re really able to work these plants through our system and get them thoroughly tested before putting them out in the market,” she adds. “It’s an exciting transition.”

The Bailey Innovations locale also allows the nursery to propagate more southern-centric plants, Roberts says. And thanks to the climate, the Georgia location gets about a month jumpstart on the season compared to Bailey’s other sites, he adds.

The Bailey Innovations site will house breeding operations and ultimately an extensive set of trial gardens, Roberts says.

“We’re still developing and building out the nursery, but we’ll eventually have production trial gardens and external trials that will include side-by-side comparisons with competitors’ plants,” Robert adds. “We’ll also incorporate display gardens to see how things perform in the landscape.”

With Bailey Innovations, the company has the opportunity to thoroughly test its genetics, Charais says.

“It’s not just about what the plant looks like in a pot. We need the ability to have more in-ground space for trialing,” Charais adds. “Having production trials is also a huge benefit to our end users. And housing all these steps under one roof at Bailey Innovations is something we’re really excited about.”

Bailey will continue to trial plants at all of its operations, including Minnesota, Oregon, Washington and Illinois, as well as at its network of growers.

Besides implementing the trial gardens, Roberts also plans to construct a temporary tissue culture lab until a permanent lab is built.

“The tissue culture lab will elevate our breeding program, and we can perform polyploid induction work for sterility breeding,” Roberts says.

Breeding focus

Bailey’s No. 1 breeding focus is Hydrangea macrophylla, Roberts says. That includes breeding around the company’s top brand, Endless Summer. And 2019 marks the 15th anniversary of the Endless Summer brand.

“We have strict criteria for a hydrangea to get into the Endless Summer brand,” Roberts says. “It must have remontancy, it must be cold hardy to Zone 4, and it must be production friendly.”

Roberts and his team are watching for unusual characteristics, such as double flowers and picotee types, including dwarf picotees. And he’d like to find a macrophylla that is cold hardy below Zone 4.

“There’s a lot of variety within macrophylla, and those differences in colors, leaves and flowers are important to the market,” Roberts says. “The market will sort out the best of the best.”

In 2019, Bailey will introduce Summer Crush, its latest macrophylla to the Endless Summer brand. It’s compact and the smallest of the five hydrangeas in the collection, and features giant, raspberry-colored blooms.

But the buck doesn’t stop with hydrangea. The First Editions brand is also on the radar for breeding efforts.

Crape myrtles, an important plant for the southern market, are being evaluated at the Georgia location.

“We’re breeding for disease resistance – especially cercospora, smaller forms, big and boisterous blooms, a rebloomer, one that’s early to flower, ease of propagation, and selections that growers can cycle prune so they’re in flower at certain times,” Roberts explains.

If the team could push cold hardiness even by one zone in crape myrtles, that would be a boon to the market, he adds.

Distylium, an evergreen shrub with five cultivars in the First Editions brand, will continue to be evaluated, as it’s an emerging genus and gaining popularity in the market.

“Bailey was first out of the gate with this genus, so we need to stay on top of it. We’ve made some Distylium crosses this year,” Roberts says.

Bailey Innovations is actively breeding vitex and looking for different flower colors.

“Flip Side vitex encapsulates what we want to do, and that’s find unique plants for the landscape,” Roberts says.

Flip Side represents a physical improvement with the bicolor on the foliage – purple-gray on the underside of the leaf and green on the top – as well as a cultural improvement because of its sterility, he adds.

Roberts can’t hide his enthusiasm regarding the future of breeding at Bailey. And he’s quick to honor the work that was done prior to his arrival.

“We inherited a gold mine from PII. They had an eye for plants and introduced things that were different and special to the market,” Roberts says. “We are taking their germplasm and introducing it into other germplasm, and we’re committed to making sure the next generation of plants meets our standards.”

Water resources will become scarcer as the world population increases, which will have an impact on how and where we use water. If consumer attitudes and behaviors severely reduce or eliminate landscape water use, it will have a widespread and detrimental effect on the green industry. Now is an ideal time to discover the role of consumer attitudes and perceptions of water use and source with regard to landscape plants. These discoveries can be used to better inform educational and marketing efforts to help sustain the green industry during drought periods and changes in water availability and consumer attitudes.

Given the increasing importance of water-related issues across the U.S., it is imperative to increase our understanding of how consumers view water conservation, especially related to the lawns and landscapes surrounding their homes. However, the evidence to date in the literature has been limited to a few states. In addition, we know relatively little about consumer behavior during real and perceived periods of drought, especially with respect to landscape plant purchases. As importantly, we do not know for sure if consumers perceive drought periods correctly, let alone whether they are likely to modify their landscape care and maintenance practices during periods of drought or if a drought influences their plant purchasing decisions at all. We developed this study to explore the answers to these questions, which will have important implications for the horticulture industry. Importantly, we do not know if consumers perceive drought periods correctly, whether they are likely to modify their landscape care and maintenance practices during periods of drought or if a drought influences their plant purchasing decisions at all.

We created an online survey, which included questions regarding a wide variety of topics related to plant and water use including plant purchases and expenditures, attitudes about water conservation and landscape plants, knowledge about water conservation and landscape plants, and demographic characteristics. We collected data September 7-13, 2016, from 1,543 participants dispersed across the U.S. who were both plant buyers and non-buyers.

We defined areas of drought using data from the National Drought Mitigation Center (Heim, 1999). This measure is used to classify levels of drought experienced at any given time across the contiguous U.S. The U.S. Drought Monitor Drought Conditions maps for Sept. 20, 2016, and Sept. 15, 2015, were chosen due to consumers’ likelihood of awareness of current drought conditions when the survey was administered (Sept. 2016) and, as another point of reference, from the previous year (Sept. 2015).

We classified the respondents into one of four groups to analyze how real and perceived drought affected attitudes and behavior related to plant purchases and water usage. We used the question, “Were you in an area that experienced drought this year?” to assess their perception of drought. We then compared their response to the drought monitor classifications to assess whether they correctly perceived being (or not being) in drought and then classified them into one of four categories: “Perceived/Real” included respondents who correctly perceived a drought when they actually experienced real drought conditions (P/R); the second category was “Not Perceived/Real” for subjects who did not perceive drought conditions but actually experienced them (NP/R); the third category was described as “Perceived/Not Real” for subjects who perceived a drought when their area actually did not experience a drought (P/NR); and the fourth category was identified as “Not Perceived/Not Real” for subjects who did not perceive a drought nor experienced one (NP/NR).

We anticipated that consumers would differ in their attitudes and behavior about plants purchases and water conservation, depending on their real and perceived drought situations, and that their attitudes would affect their plant purchases. For example, people classified in the P/R category might show a different attitude about water conservation and behavior, especially compared to subjects in NP/NR category who may not be as concerned about water use. Individuals in the NP/NR category were described as “in normal conditions”. Respondents in the NP/NR category may show similar attitudes and behavior to the individuals in the P/NR since they perceived a drought, even though they really were not experiencing one. We were interested in the NP/R respondents since those respondents may lack knowledge about the real drought occurring in their area and could be using more water or have different perceptions about drought. We believed that people in the NP/R group would be different demographically, spend more on plants (because they may not have known they faced water restrictions), and engage in less positive water conservation attitudes compared to other groups.

The average age of respondents was 40 years old and most were women (57.8 percent). Average household size had 1.2 adults and one child every two households. Respondents were primarily Caucasian (87 percent) and approximately a third (28.3 percent) had earned a 4-year college degree. This is relatively comparable to a sample of the U.S. at large.

We found that 16.4 percent of our respondents could be classified in the group P/R (correctly perceiving they were in a drought situation), 29.1 percent were in the group NP/NR (correctly perceiving they were not in drought or under normal conditions), 52.3 percent were classified in the group NP/R (not aware they were in drought), and only 2.0 percent were in the P/NR group (incorrectly believing they were in drought). Since the NP/NR respondents were accurate in their perception that they did not experience a drought, we used this group as a “control” or “benchmark” against which we compared the other groups. Those in the P/R were accurate in that they perceived a drought when they were really in a drought situation. With such a small number of respondents in P/NR group, they were excluded for the analysis.

Demographically, the remaining three groups were similar on most of the listed demographic characteristics. However, the NP/NR spent most on plants in 2015 followed by NP/R and then P/R in 2015 (Figure 1). We did see decreased plant spending on plants for the P/R group and more plant expenditures for the NP/NR or “normal” group. Next, we asked what types of plants were purchased in 2016 (Table 1) and found that annuals were the dominant plant category purchased (by 49.8 percent of the respondents overall), followed by vegetables (41.6 percent), herbs (30.5 percent), perennials (29.7 percent), and flowering shrubs (19.2 percent). A much smaller percentage of subjects in each category had purchased evergreen shrubs (7.4 percent overall), fruit trees (9.3 percent), evergreen trees (6.8 percent), and shade trees (7.5 percent). Very few differences between the groups were observed, with each of the 3 groups exhibiting similar percentages of purchases for annuals, perennials, flowering shrubs, and fruit trees. However, a higher percentage of the P/R group purchased evergreen trees and shrubs compared to the other two groups. The higher incidence of purchase for evergreen shrubs and trees for those who correctly perceived drought during real drought conditions may partly be explained in that some evergreens (not broad leafed types) may require less water to establish after transplanting.

All three groups had a similar percentage of individuals with a lawn and landscape, and patio/porch area, as well as those who had neither (only 7 percent overall) but they differed in whether they irrigated turf and/or landscape beds (Figure 2). A higher percentage of survey participants in the P/R irrigated turf and landscape beds, most likely because the householder may have believed that the turf or landscape may not have survived without it. While we didn’t measure water use, we could suspect that people in the P/R group may be using more water to sustain their plants and turf. Approximately 1/3 of the people in P/R drought irrigated plants to keep them alive. For green industry growers and retailers, the need to use irrigation in an effective manner and to adopt water-saving measures (e.g. mulching, adoption of low-water use cultivars) appears to be essential to the long term sustainability of the Green Industry.

We found some attitudinal differences between the three groups (Table 2). When asked whether they thought water conservation was important, all three groups strongly agreed with the statements and had generally positive attitudes about water conservation. However, we found a higher level of agreement to the statements in the NP/NR groups. This average level of agreement was higher compared to both P/R and NP/R. A similar pattern was found when asked if water conservation was of great concern. Interestingly, when asked if they “know a lot about water conservation” and if they “conserved water in and around their home,” there were differences among all three groups but the P/R group ranked the lowest. Both the P/R and NP/R groups were lower than the NP/NR group for the questions about water conservation practices, including “I use fixtures that help me conserve water at home,” “The price of water restricts what I can do in the landscape areas outside my home,” and “I have decreased my outdoor plant purchases due to water restrictions in my neighborhood.” The only question in which there were no differences stating “In a water crisis, we should not buy or try to maintain outdoor landscape plants” with all three groups moderately agreeing with this statement.

The more people become aware of a drought, the more they may realize they do not know how to deal with their plants in a drought.

This difference in attitude observed among the groups may be partly explained by the Hierarchy of Competency (Adams, 2017). According to this theory, individuals begin as unconsciously incompetent and are initially unaware of what they do not know. The theory then posits that they gradually recognize they have a knowledge deficit, to knowing how to handle the knowledge deficiency. They may further develop to unconscious competency where the “skill” or knowledge is second nature. Though we expected P/R to be most sensitive to drought conditions, this would not necessarily be true by the “order of recognition.” What we conclude from these results is that subjects in the P/R group demonstrate conscious competency the consciously competent stage by being aware of the drought and having the knowledge to adjust their lifestyles or being aware of their lack of knowledge or ability adjust to drought conditions. NP/R may demonstrate unconscious incompetency the unconsciously incompetent stage, where they do not know their deficit of knowledge and therefore are not sensitive to drought information and issues. Finally, NP/NR may demonstrate being consciously competent of their drought conditions. They recognize their drought status but it is also possible that they have experienced drought conditions or have prior knowledge and are sensitive to drought information and issues.

We speculate that maybe the more people become aware of a drought, the more they may realize they do not know how to deal with their plants in a drought. Beal et al. (2013) observed when people who are over or under-estimating their water usage are made aware of their actual water usage (education/awareness) they could change their habits. But, technology engineered to assist with water conservation needed to be tied to water conserving behavior – not used as a crutch. There is a paradox in which the more consumers who underestimate water use are made aware of their behavior, the more they realize they do not know.

In addition, we know relatively little about consumer’s landscape plant purchase behavior during real and perceived periods of drought. Our goal was to better understand consumer behavior during real and perceived drought situations, especially in terms of their landscape purchases and gardening/landscaping activities. We hypothesized that consumers would be similar in their attitudes and behavior regarding plants and water conservation, depending on their real and perceived drought situations, and that their attitudes would affect their plant purchase behavior. Findings from this study confirmed this hypothesis. For example, people classified in the P/R category demonstrated a different attitude about water conservation and plant purchasing behavior, compared to subjects in the NP/NR category. More education is still needed to help facilitate the transition from intensively managed landscapes to include the use of plants or cultivars that use less water. Growers, wholesalers, and retailers will benefit from leading some of this change by promoting the water use needs of plants, especially those with lower use, and continuing to communicate water sources in plant production as well as landscape water needs.